Observation of minority-carrier drift by infrared radiation

Two-dimensional imaging of a minority-carrier packet is reported. Displacement of the minority carrier according to the clock pulse can be visualized. Utilizing the sampling gate technology, it is possible to analyze the timing operation of digital circuits. The advantage is that it is accessible to any point on the chip, requiring no direct contact probing or vacuum system. There is no interaction with the circuit operation. The disadvantage is that some integration time is inevitable due to very weak emission. For GaAs ICs, however, the emission efficiency as well as sensitivity of the photocathode is very much higher. Thus, almost real-time imaging is possible